Southern Cross Medical Library

The purpose of the Southern Cross Medical Library is to provide information of a general nature to help you better understand certain medical conditions. Always seek specific medical advice for treatment appropriate to you. This information is not intended to relate specifically to insurance or healthcare services provided by Southern Cross. For more articles go to the Medical Library index page.

Post-polio syndrome

Post-polio syndrome (PPS) is a chronic (long-term) condition of the central nervous system (brain and spinal cord). As its name suggests, it occurs following infection with the contagious polio virus (poliomyelitis) which affects the central nervous system and can cause paralysis.

Epidemics of polio occurred during the 1940s and 1950s. Since the widespread introduction of polio vaccines, the condition has largely been eradicated in the Western World. The World Health Organisation (WHO) has targeted the eradication of polio and by 2006 there were only four countries in which it was still prevalent.

In the 1970s many survivors of the polio epidemics noticed new problems such as muscle weakness, increasing fatigue, decreased endurance for activity and painful muscles. The terms “post-polio syndrome”, “post-polio sequelae” or “late effects of polio” were coined to describe the phenomenon.

PPS is usually diagnosed 20 to 40 years after the initial polio infection but not everyone who has had polio will develop PPS. In New Zealand it is estimated that there are 3000 to 5000 polio survivors of whom between 25% and 50% will suffer from PPS.

Signs and symptoms

PPS usually develops gradually over a period of years. In some cases, however, the condition can occur more suddenly over a period of months. Signs and symptoms vary in duration and severity and can include:

Causes

During polio infection the nerves that carry electrical impulses from the central nervous system to muscles are weakened or destroyed. These nerves are known as the motor neurons. The electrical impulses they carry cause the muscles to contract, which produces movement. When motor neurons are damaged, paralysis can result. Movement is regained with the partial recovery of infected motor neurons. And neighbouring non-infected motor neurons can increase in size and/or “sprout” new connections to muscles.

In PPS it is thought that as polio survivors age these restructured neuromuscular connections begin to fail. It is also thought that impaired production of certain hormones and chemicals that assist with the transmission of nerve impulses may be related to the development of PPS. The onset may also be triggered by trauma such as emotional upheaval, an accident or undergoing surgery. There is no evidence to suggest that PPS is due to reinfection with the poliomyelitis virus.

Who gets post-polio syndrome?

PPS tends to occur more frequently and more severely in individuals who were worst affected during the initial polio infection, but made the best recovery. Other factors that increase the risk of polio survivors developing PPS include:

Recent weight gain

Being over 10 years of age at the time of the initial polio infection

Having a newly diagnosed medical problem

The worsening of an existing medical condition

A recent accident or injury

Recent surgery

Increased stress

Diagnosis

The symptoms of PPS can resemble those of other conditions. It is therefore necessary to rule out other possible causes for these symptoms before a diagnosis of PPS can be made. To assist with diagnosis the doctor will take a full medical history and assess current signs and symptoms. This history will indicate a confirmed episode of paralytic polio, typically followed by recovery and a period of at least ten years of stability until symptoms of PPS are first noticed.

There is no one definitive test for diagnosing PPS. An electromyogram (EMG) may be recommended to measure changes in electrical activity in the muscles consistent with prior polio infection. Other tests include MRI (magnetic resonance imaging), muscle biopsies and blood tests.

Treatment

At present there is no cure for PPS. Treatment is aimed at modifying activities that result in symptoms such as fatigue, muscle weakness and pain. This includes:

Lifestyle changes eg: working part time instead of full time, taking daytime rests

Avoiding activities that produce fatigue and discomfort

Undertaking exercise that is non-fatiguing and does not produce pain

Recognising pain as a warning sign to stop and rest

Using medications to assist with the management of pain eg: anti-inflammatory medications (long-term use of these medications should be avoided)

If swallowing is a problem, eat small meals frequently and avoid eating when tired

Speech therapy can also be useful, especially if swallowing difficulties are associated with speech impairment.

In cases where PPS causes significant breathing difficulties, hospitalisation and the use of a ventilator (a mechanical device to maintain breathing) may be required.

In all cases, healthcare professionals such as physiotherapists and occupational therapists can advise on appropriate exercise, activity and lifestyle modifications.

Research has been conducted into the use of various medications in the treatment of PPS, but no effective treatment has yet been identified. Research to identify effective treatments for PPS continues, with many studies looking at nerve growth factors.

Further support

For more information on PPS please contact your doctor or the Post Polio Support Society of New Zealand: